I have a 1991 Toyota Pickup 2 weeks ago the battery went dead for some reason, I found out it was the alternator wasn't charging. I had it fixed under Warrenty {I had the alternator replaced less than a year ago}
I recharged the battery and everything was fine, until the 4 days ago, the battery went dead again I cheched the alternator and it was charging the following morning I checked it again and the alternator was NOT charging. I charged the battery again and everything seemed ok. This morning I went out and the battery was low again and the alternator's not charging again..... Any thoughts on what could be wrong? This is driving me nuts having to charge the battery so much

Could be something as simple as a corroded connector where the alternator plugs in.
My brother went through 3 alternators on his '99 Ford F-250 and finally he took it in to the dealer and they found that the problem was the connector that went to the voltage regulator on the alternator.
I would suggest taking it to a mechanic whom you trust and let them figure out why its not charging.

I have had all connectors off and checked when I replaced the Alternator nothing is corroded or loose,
anyone know where the voltage reg is on my truck?
its a 1991 Toyota Pickup

just wondered if you are still having to charge your battery all the time, cos I am and getting a bit sick of it,but being an optimist, kind of hoped driving thrtough a load of puddles or crashing gently into something would solve my battery charging problems, any other suggestions would be appreciated.(preferably not fitting a new alternator!)

a simple useful alternator test. with your car running at idle and no accessories, lights, ect. on. disconnect your positive battery cable . the car should stay running if your alternator is functioning correctly. If it is. leave your battery disconnected from the alternator for the night. (or for however long it has been taking to drain the battery.) Reconnect in the morning and see if it starts. Quite often alternators fail because a strain is being imposed on them by a shorting battery. It's good practice to replace both at the same time.

I had a mustang that I had just put a new altenator in and it was bad right off the bat. Then I recently replaced the altenator in my truck and it only lasted for 2 months. The bottom line is you could have just got a bad altenator, it has happen to me multiple times.

Using a voltmeter, check your voltage across you battery. Should read 12-13 volts.

Then start your vehicle and probe the battery again. Should read approx 15 V.

This is a very simple way to see if your alternator is trickle charging your battery. Takes 30 seconds.

Option 2, remove your alternator and take it to a rebuild shop. For $5 they will test it, and for another $40 they will rebuild it....if necessary.